An announcement was recently made during an event in Gurgaon, India that offline YouTube videos would soon become a possibility. This means that people watching videos on YouTube in India will be able to download content and watch it whenever they like. This is a feature not currently available in North America or Europe, unfortunately (with the exception of the YouTube Music Key subscription).
In the next few weeks these offline YouTube videos will become available without data so people can watch anytime, anywhere. YouTube exec Ceasar Sengupta explained "You can download a video once, save it to your phone, and watch it again and again."
No further information has been released in regards to how advertising will work or if this feature will be coming to any other countries outside of India.